ASTM_C_1046_-_95_2013.pdf

Designation:C104695(Reapproved 2013)Standard Practice forIn-Situ Measurement of Heat Flux and Temperature onBuilding Envelope Components1This standard is issued under the fixed designation C1046;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers a technique for using heat fluxtransducers(HFTs)and temperature transducers(TTs)in mea-surements of the in-situ dynamic or steady-state thermalbehavior of opaque components of building envelopes.Theapplications for such data include determination of thermalresistances or of thermal time constants.However,such usesare beyond the scope of this practice(for information ondetermining thermal resistances,see Practice C1155).1.2 Use infrared thermography with this technique to locateappropriate sites for HFTs and TTs(hereafter called sensors),unless subsurface conditions are known.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2C168 Terminology Relating to Thermal InsulationC518 Test Method for Steady-State Thermal TransmissionProperties by Means of the Heat Flow Meter ApparatusC1060 Practice for Thermographic Inspection of InsulationInstallations in Envelope Cavities of Frame BuildingsC1130 Practice for Calibrating Thin Heat Flux TransducersC1153 Practice for Location of Wet Insulation in RoofingSystems Using Infrared ImagingC1155 Practice for Determining Thermal Resistance ofBuilding Envelope Components from the In-Situ Data3.Terminology3.1 DefinitionsFor definition of terms relating to thermalinsulating materials,see Terminology C168.3.2 Definitions of Terms Specific to This Standard:3.2.1 building envelope componenta portion of the build-ing envelope,such as a wall,roof,floor,window,or door,thathas consistent construction.3.2.1.1 DiscussionFor example,an exterior stud wallwould be a building envelope component,whereas a layerthereof would not be.3.2.2 thermal time constantthe time necessary for a stepchange in temperature on one side of an item(for example,anHFT or building component)to cause the correspondingchange in heat flux on the other side to reach 63.2%of its newequilibrium value where one-dimensional heat flow occurs.Itis a function of the thickness,placement,and thermal diffusiv-ity(see Appendix X1)of each constituent layer of the item.3.2.2.1 Discussiont 5 when qt!5 q11q22 q1!l 2 et/!where:q1=is the previous equilibrium heat flux,andq2=is the new heat flux after the step change.3.3 Symbols Applied to the Terms Used in This Standard:E=measured voltage from the HFT,typically in mV,q=heat flux,W/m2(Btu/hft2),S=heat-flux transducer conversion factor that relates theoutput of the HFT,E,to q through the HFT for theconditions of the test,W/m2V(Btu/hft2mV).Thismay be a function of temperature,heat flux,and otherfactors in the environment as discussed in Section 7.This may also be expressed as S(T)to connote afunction of temperature,T=temperature,K(C,R,or F),1This practice is under the jurisdiction of ASTM Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.30 on ThermalMeasurement.Current edition approved Nov.1,2013.Published January 2014.Originallyapproved in 1985.Last previous edition approved in 2007 as C1046 95(2007).DOI:10.1520/C1046-95R13.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 t=time,s(hours,days),and=thermal time constant,s(hours,days).4.Summary of Practice4.1 Heat flux transducers are installed on or within abuilding envelope component in conjunction with temperaturetransducers,as required.Heat flux through a surface is influ-enced by temperature gradients,thermal conductance,heatcapacity,density and geometry of the test section,and byconvective and radiative coefficients.The resultant heat fluxesare determined by multiplying a conversion factor S of the HFTby its electrical output.The S values shall have been obtainedaccording to Practice C1130.5.Significance and Use5.1 Traditionally,HFTs have been incorporated into labora-tory testing devices,such as the heat flow meter apparatus(TestMethod C518),that employ controlled temperatures and heatflow paths to effect